1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. The present invention relates to a process, a machine, manufacture, or a composition of matter. In particular, one embodiment of the present invention relates to a display device, an input/output device, a semiconductor device, a light-emitting device, an electronic device, a lighting device, a driving method thereof, or a manufacturing method thereof. In particular, one embodiment of the present invention relates to a display device (display panel). One embodiment of the present invention relates to an input/output device, a semiconductor device, an electronic device, a light-emitting device, or a lighting device that includes a display device, or a manufacturing method thereof.
In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. A transistor, a semiconductor circuit, an arithmetic device, a memory device, and the like are each an embodiment of the semiconductor device. In addition, a light-emitting device, a display device, an electronic device, and a lighting device each may include a semiconductor device.
2. Description of the Related Art
It is known that an active matrix liquid crystal display device is classified into two major types: transmissive type and reflective type. In the transmissive liquid crystal display device, a backlight such as a cold cathode fluorescent lamp or a light emitting diode (LED) is used, and optical modulation action of liquid crystal is utilized to select one of the two states: a state where light from the backlight passes through liquid crystal to be output to the outside of the liquid crystal display device and a state where light is not output to the outside of the liquid crystal display device, whereby a bright or dark image is displayed. Furthermore, those images are combined to perform image display.
In a reflective liquid crystal display device, a state in which external light, that is, incident light is reflected at a pixel electrode and output to the outside of the device or a state in which incident light is not output to the outside of the device is selected using optical modulation action of liquid crystal, whereby bright and dark images are displayed. Furthermore, those displays are combined to display an image. Compared to the transmissive liquid crystal display device, the reflective liquid crystal display device has the advantage of low power consumption since the backlight is not used. Patent Document 1 discloses a flexible active matrix light-emitting device in which a transistor and an organic EL element are provided over a film substrate.